libstdc++: Use RAII in std::vector::_M_default_append

Similar to r14-2052-gdd2eb972a5b063, replace the try-block with RAII
types for deallocating storage and destroying elements.

libstdc++-v3/ChangeLog:

	* include/bits/vector.tcc (_M_default_append): Replace try-block
	with RAII types.

diff --git a/libstdc++-v3/include/bits/vector.tcc b/libstdc++-v3/include/bits/vector.tcc
index cda52fbbc4a1bf2dd63f5d00d7268ce933f31f0c..f592c72dec242664ce91a7a2fdf4ea0ed06d6a21 100644 (file)
--- a/libstdc++-v3/include/bits/vector.tcc
+++ b/libstdc++-v3/include/bits/vector.tcc
@@ -704,47 +704,74 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
              const size_type __len =
                _M_check_len(__n, "vector::_M_default_append");
              pointer __new_start(this->_M_allocate(__len));
+
+             // RAII guard for allocated storage.
+             struct _Guard
+             {
+               pointer _M_storage;         // Storage to deallocate
+               size_type _M_len;
+               _Tp_alloc_type& _M_alloc;
+
+               _GLIBCXX20_CONSTEXPR
+               _Guard(pointer __s, size_type __l, _Tp_alloc_type& __a)
+               : _M_storage(__s), _M_len(__l), _M_alloc(__a)
+               { }
+
+               _GLIBCXX20_CONSTEXPR
+               ~_Guard()
+               {
+                 if (_M_storage)
+                   __gnu_cxx::__alloc_traits<_Tp_alloc_type>::
+                     deallocate(_M_alloc, _M_storage, _M_len);
+               }
+
+             private:
+               _Guard(const _Guard&);
+             };
+             _Guard __guard(__new_start, __len, _M_impl);
+
+             std::__uninitialized_default_n_a(__new_start + __size, __n,
+                                              _M_get_Tp_allocator());
+
              if _GLIBCXX17_CONSTEXPR (_S_use_relocate())
                {
-                 __try
-                   {
-                     std::__uninitialized_default_n_a(__new_start + __size,
-                             __n, _M_get_Tp_allocator());
-                   }
-                 __catch(...)
-                   {
-                     _M_deallocate(__new_start, __len);
-                     __throw_exception_again;
-                   }
                  _S_relocate(__old_start, __old_finish,
                              __new_start, _M_get_Tp_allocator());
                }
              else
                {
-                 pointer __destroy_from = pointer();
-                 __try
-                   {
-                     std::__uninitialized_default_n_a(__new_start + __size,
-                             __n, _M_get_Tp_allocator());
-                     __destroy_from = __new_start + __size;
-                     std::__uninitialized_move_if_noexcept_a(
-                             __old_start, __old_finish,
-                             __new_start, _M_get_Tp_allocator());
-                   }
-                 __catch(...)
-                   {
-                     if (__destroy_from)
-                       std::_Destroy(__destroy_from, __destroy_from + __n,
-                                     _M_get_Tp_allocator());
-                     _M_deallocate(__new_start, __len);
-                     __throw_exception_again;
-                   }
-                 std::_Destroy(__old_start, __old_finish,
-                               _M_get_Tp_allocator());
+                 // RAII type to destroy initialized elements.
+                 struct _Guard_elts
+                 {
+                   pointer _M_first, _M_last;  // Elements to destroy
+                   _Tp_alloc_type& _M_alloc;
+
+                   _GLIBCXX20_CONSTEXPR
+                   _Guard_elts(pointer __first, size_type __n,
+                               _Tp_alloc_type& __a)
+                   : _M_first(__first), _M_last(__first + __n), _M_alloc(__a)
+                   { }
+
+                   _GLIBCXX20_CONSTEXPR
+                   ~_Guard_elts()
+                   { std::_Destroy(_M_first, _M_last, _M_alloc); }
+
+                 private:
+                   _Guard_elts(const _Guard_elts&);
+                 };
+                 _Guard_elts __guard_elts(__new_start + __size, __n, _M_impl);
+
+                 std::__uninitialized_move_if_noexcept_a(
+                   __old_start, __old_finish, __new_start,
+                   _M_get_Tp_allocator());
+
+                 __guard_elts._M_first = __old_start;
+                 __guard_elts._M_last = __old_finish;
                }
              _GLIBCXX_ASAN_ANNOTATE_REINIT;
-             _M_deallocate(__old_start,
-                           this->_M_impl._M_end_of_storage - __old_start);
+             __guard._M_storage = __old_start;
+             __guard._M_len = this->_M_impl._M_end_of_storage - __old_start;
+
              this->_M_impl._M_start = __new_start;
              this->_M_impl._M_finish = __new_start + __size + __n;
              this->_M_impl._M_end_of_storage = __new_start + __len;